IIA-UR“74 ZYi7

z%~. 7)4446--.7TITLE: STUDIES OF THE APPARENT VOLUBILITY OF 23%U02

MICROSPHERES IN AN AQUATIC ENVIRONMENT AND THEUPTAKE OF PLUTONIUM FROM A SOIL MATRIX CONTAINING238PU02

●

AUTHOR(S): W. H. Adams and E. B. Ftmler

SUBMIITEDTO: SECOND AEC ENVIRONMENTALAlbuquerque, New Mexico,

PR~ECTI~ CONFERENCEApril 16-19, 1974

JI almmosBcIontific laboratory

of tha University of CaliforniaLOS ALAMOS, NEW MEXICO 87544

.~\.

mmNo. Wet. No. 26?5/73

Thu report wu prepmd ● an cccowtr of wmktpoworad by the IJnlwd Smloa Governrnonc. Nolmarm. Unlwd Smm nor ItM United Smm Alomk EMrCYCommlulon. nor my of thou cmptoyoos, rim ut~ ofIh@lr conrraclws, wbcontrwtom w tbk ●MPbYM’S.mka SIIJ $wmnt). ●xProu a ImMd, of -~m- MYIeral Imblllti w responmbilltv for tha accurUY. com-platcnc~ or umfrdnew of any lnformmlal, SPPMSIUS.prduci or IMO.aM Jlsclnsed, ur rsprwwrts that It@ wwuld nut Infrtn@ privalely owwd rlrht.s.

ti!llf!n’[~

.

UNITED 8TATC9ATOMIC CNCRGY CO MM IS,IOM

CONTRACT M-740 S-RN~, t?IsTRIWJTiON (X WiS POCUhlE~4T IS LJNLI, EDY

STUDIES THE OF 23*PU02

MXWSPHE~S IN AN AQUATIC ENW~NMEFiT AND THE

UPTAKE OF PLUTONIUM FROM A SOIL MATRIX CONTAINING238PU02

W. H. Adam and E. B. FowlerHealth Division

IOS Alamos Scientif~c LaboratoryUniversity of CaliforniaLos Alamos, New Mexico

ABSTRACT

The uptakeof plutonim by lettuceand barley from238

soil spikedWith PU02 microaphereais described. A

fouryear studyof the effectof simulatedsoil stressesof plant ash,

on the concentrationfacto= of plutoniw (WwqVdg of soil

is presented.238

The ‘appmnt” EJOlubility-of PU02 ticrosphere9in

tap water in determinedand the de~iton of plutonium

in fish,algaeand snailsin quaria containing238PU0

‘1

microsphere is reported.

These data may be used to

with the lossof a Systenmfor

device.

INTRODUCTION

&

amesa the hazardassociatal

NuclearAuxiliary Pmer

The use of 238PU02 microsphere in Systems for Nuclear

Auxiliary Power (SNAP) devices prompted a study of the

effect which accidental deposition of these microsphere on

soi1 and plants might have upon the uptake and translocation

of plutonium in plants. Later the study waa expanded to

include the volubility of 238PuC)2microsphere in water and

the deposition of plutonia in fish.

1. SOILS SPIKED WITH 238Pu02 MICR~PHIZRES

The experi~ntal work was initiated to study both the

translocation of plutonium in plants contaminated with 238PU02

microsphere and the plant uptake of plutonium from soils

238centaining PU02 microspheres. H~ver, the “in plant”

tra.nslocationstudies were terxninated after a few days since

the 100 v dizumter microsphere contained enough plutonium

to burn the plant tissue.

Thompson1 likewise found that 238Pu02 microspheres

burned holes in African violet leaves causing microsphere

to drop through the leaf. Visible damage to the leaves was

noticeable on the second or third tiayof exposure.

In the plant uptake studies, Los Alamos mountain meadow

soil, wh.{chcontained 5% organic matter and 0.24% nitrogen,

was air dried and screened; the portion not passing through

a 20 mesh screen was discarded. Twelve hundred grams of the

sieved, air dried soil were spiked with 25.6 mg of 238PU02

microsphere and mixed in a large “V” shell blender for five

hours. These microsphere were obtained from Mound Laboratories

approximately July 1965 and are designated only as Batch #1

since no other more definitive notation was available. After

“lacing 800 to 900 grams of unspiked soil in a plasticL’”

containex 15 cm in diameter and 13 cm deep, two hundred

grams of the spiked soil were added to the container, then

the spiked soil was covered with another 800 to 900 grams

-2-

of unspiked soil.

manner; three were

.

Six plastic pots were treated in this

planted to lettuce and three were planted

first to oats and later to barley.

The miniature SCJi 1 plots were then placed inside a

lucite growth chtier 1.22 ntetres long, 0.91 rnetreshigh and

0.91 mtres deep. The chamber was used as a precautionary

measure to keep the microsphere centained and to keep the

plants isolated from the other plants grown in the green-

house. The lucite box was equipped with two 15 ~ Ma.

meter portholes with movable covers. Two exhaust fens

mounted to the box exhausted air through a filter into the

greenhouse. The portholes were used as access holes so that

p?.antwatering and hamesting could be achieved. Clean

surgeons g.bves were used when watering or harvesting the

plants ● Whenever possible the plants were cut at such a.

height that successive cuttings could be obtained from a

single planting.

After hanesting two lettuce crops and three oat crops,

the soi1 plots were allaved to lie fallow before being

replanted to lettuce and barley on the 474th day after the

original soil was spiked. After hanesting an additional

lettuce and barley crop the soi1 plots lay fallow for 55 days

and then were placed in a plastic bag and allmed to remain

outdoors for the next six months (March 21, 1967 to September

21, 1967]. The plots were next planted to lettuce and

barley and two crops were harvested.

-3-

.

The miniature soi1 plots were next frozen with dxy ice

and allowed to thaw at room temperature; this procedure was

zepeated ten times before the “soi1 was again planted to

lettuce and barley. Five crops were hanested beg%nning

with the barley ha~s”t on the 89Oth day after the soi1 was

spiked. The plots then lay fallw for 80 days before being

replanted. Two crops were “h~sted and another 186 days

passed before the final planting was made on the 1 374th day

after the soil was spiked. A final crop was h~sted .70

days later, concluding a study initiated about four years

earlier.

All of the plants grown in this study were ashed at

600°C to destroy the organic.matter present in the samples.

The plant ash, howkver, was leached with 8 M HN03 and the

plutonium separated from the dissolved salts .by an -nion

exchange technique. The plutonium was electrodeposited from

an HC1 - (NH4)2C204 solution ad counted i~ an alpha scinti1=

lation counter.

A. Discussion

Although the238

PU02 microsphere placed in the soi1 wers

weathered an~ exposed to other stresses in the soi1, very

little plutonium was converted to a “soluble” form as shown

by the limited uptake of plutonium by the plants (Table 1).

Three kg of fresh lettuce and about O.9 kg of green bar-

ley, grown in soi1 contaminated with plutonium to the level

used in these experiments, would contain the same amount of

-4-

.

FROM SOIISSPIKEDWITH 238PU0-

Crorl

Let tuceOatsLettuceoatsOatsmttuce (2)

Bulq (2)Lettuce(s)“Barley(3)LettuceBuleyB~ley (4)Lettuce “BarleyIattuceBarleyU!ttuca -BarleyLettuceB~leyLettuce(5)Barley(5)LettuceBarleyLettuce(6)B~ley

Day? Time PlutoniumFrom Spike MV9TO Harvest of Ash

7474145145186544

544811811.825825890909909949949992992

1 0191 0191 1481 1481 1881 1881 4441 444

Lettuce

Av Cone. 8.4 X 10-8Factor e.1 x 10-8All Crops

1372.7 “80.7823.5

I&!ssthancontrol

9.525.67.136.41.61.531.25.719.99.215.525.229.550.6169.950.888.484.4143332

Barley

7.4 x 10-87.3 x 10-8

1.8 X 10“8

1.0 x 10-71.1 x 10-71.2 x 10-75.0 x 10-9

1.3 x 10-83.6 X 10-81.0 x 10-85.2 X 10-82.3 X 10-92.1 x 10-94.4 x 10-88.1 X 10-92.8 x 10-81.3 % 10-82.2 x 10-83.6 X 10-84.2 x 10-87.2 x 10-82.4 x 10+7.2 x 10-81.3 x 10-71.2 x 10-72.0 x 10-7 “4.7 x 10-7

Oats

7.5 x 10-87.2 X 10-8

(1) ~oncen~rationfactor is d/m/g of plantash ~ d/n/g of soil.

(2) Soil lay faliowfoz approximatelynineand one halfmontlw- replantedat about .--r ..474 d~aysafter soil spike.

(3) First harvestaftersix mn~~s weather-ing Out Or doo~~.

(4) ri=t harvest after el~vcnfreeze-thd~cycles.

(5) Firs:harvestaftersoils lay fallowfor 8? days.

(6) Final harvest of crops planted at 1 374daya after soils lay fallow for 186 days.

#

238PU as e~~essed by the maximum permissible concentration

2of plutonium per liter of drinking water for public use.

Such plutonium concentrations in lettuce and barley were

calculated using the highest pl-itaniumconcentrations found

in the analyses of the different crops (1 444 day barley,

i.e. 322 d/m/g” 1 140 day lettuce, i.e. 170 “d/@g (Table l; I

and the values of 2.1% and 4.0% ash for lettuce and barley.

respectively.

If 10 kg of238PU02 micr~pheres were mixed uniformly

with soil by plowing to a depth of 15 an, then one acre of

soi1 would be contaminated with the same concentration of

238Pu as that used in these experiments. However, experience

has shan that the high altitude loss of a SNAP device did

nti result in high level contamination of a relatively small

area of soil but rather in an almost uniform distribution

of 238PU02 as fallout upon the earth.3 Such la ievels of

238Pu contamination would not result in ~asurable amounts

of 239Pu in plants as a result of plant uptake based on

results obtained in the experiments described and summar-

ized in Table 1.

II. PL~~lIUM IN AN AQUATIC ENVIRONMENT

A. Plutonium Incorporated ifiFish

To determine the effect of238

PU02 microsphere on an

aquatic environment in the event of accidental release of

plutonium from SNAP devices, microsphexes of the radionuclids

were placed in aquaria containing goldfish; two separate

238studies were made, each with a different batch of PU02

-5-

ndcrospherea. One study involved the use of ficrospheres

from Batch #2* which had shown ~ gn water ‘solubilityn studies~

a tendency to lose activity to the surrounding water. In the

second study, m.icrospheresfrom Batch #1* used in the soil

plots described in Part I were used. The designation of

Batch #1 and Batch #2 is made only to indicate two different

preparations and that all 238PU02 microsphere are probably

not alike and that differences in uptake and ~solubility”

can occur because of these differences.

In the study using Batch #2 microsphere, each of the

three aquaria was spiked with me238

PU02 microsphere which

was about 100 v in diameter and was calculated to contain

8about 1.82 x 10 d/m total alpha activity. Each microsphere

was placed beneath the sand filter support inside a 40 ml

pyrex beaker which had been cut so that the side wall

height was about 2 to 3 mm. The microsphere was thus easily

retrievable and was still exposed to the circulating water

currents caused by the air bubblers attached to the filter

supports. The three aquaria contained six fish each; an

additional six goldfish, which died before the aquaria were

ready for stocking, were analyzed for plutonium and thus

served as a plutonium concentration base line for fish not

238exposed to PU02 ● One figh from aquarium ‘onew died after

the first three days, during which time it had accumulated

“~o other designation could be determined for the two batchesof microsphere.

-6-

nearly two hundred times rnoxe

unexposed fish. A fish which

in aquarium “three” contained

plutonium than found in the

died after six days exposure

four hundred tifiesmore plu-

tonimn than the average unexposed fish (see 1st 6 fish and

fish #J8,Table 2).

Each fish thereafter from #9 through #15, whether it died

of natural causes or was sacrificed, was analyzed for plu-

tonium as a whole sample. The 16th, 17th, and 18th fish were

dissected such that the gills, gut and contents, flesh, and

bones could be analyzed separately for plutonium. In all

instances the whole fish or the fish parts were dried at

llO°C for about 12 hours, then ashed at 600”C. The ash was

leached with 8 N HN03 and the plutonium determined by the

anion exchange separation.

The water in the aquaria was assayed for plutonium period-

ically by removing a 1 000 ml aliquot which was then acidified

with HN03 and evaporated to dryness; the residue was leached

with 8 M HNO”3and the resulting leach solution taken to dry-

ness. The plutonium was converted to the tetravalent nitrate

complex by the addition of concentrated HN03 aridH202 after

which the sample was taken to

residue was taken up with 8 M

from the salts in solution by

dryness on a steam bath. The

HN03 and the plutonium separated

anion exchange techniques.

The water taken from the aquaria periodically for pluto-

nium analysis was replaced with an equal volume of chlorine-

free tap water. Evaporative losses which occurred during the

-7-

TABLE 2.

23*Pu IN FISH AND FISH ORGANSBATCH NO. 2 MICROSPHERES

Days Exposure d/m/q Ash d/m/g of Ashed Organ

Gutand

Gills Contents Flesh Bones——

to H20 Contg. Microspheres- Activity Foundin Whole Fish

FishNo.

1st 6

7

8

9

10

11

12

13

14

15

16

17

18

238PU02 Total

Fish.—

0

3

6

6

7

9

10

14

15

17

31

45

48

7.0 -- --- 9- 9-

10-53.9

1.3

1.2

6.8

..1.8

3.4

2.5

3.8

1,5

2.6

6.7

2.”3

1,435x

x

x

x

x

x

x

x

x

x

x

x

-- -- -- 9-

10-4 2,836 --

--10-5 521

10-6 302 --

--

9.

--

--

--

10-4 14,935

10-5 1,566

10-5 --

--10-5 3,512

10-5 611 9-

306

443

-- 2,935

--

7?488

39,800

36,142

--

10-5 476 309

10-6 239 138--

10-5 292 332

(continued on next page)

TABLE 2

!wm!sQ WW9 of Ashed OrganDays Exposure %to H20 Contg. MicroSpheres

23SPU02 Activity--Found

in-Wh”oleFish

Gutand

FishNo ●

Flesh . BonesContents

49 8.7 X 10-6

104 1.4 x 10-5

181 “ 1.8 x 10-5

19 9- 246 3,000 376

602

994

537

320

153

-- 21,000 18,0J0 73

21

22

-- 94 2,818 304

183 2.0 x 10-4

184 6.6 X 10-5

99 2,770 32,110 119

23

24

-- 6,750 52,630 462

185 2,7 x 10--6 -- 2,360 51,940 462 191

-.

.

studies were compensated for by @ding distilled water.

At the conclusion of the experiment (six months) , the entire

liquid content of each aquarium was removed and analyzed

for plutonium h the same manner as the 1 000 ml samples

described above. The “volubility” or amount of plutonium

lost from the microsphere and found in the aquarium water is

presented as a percentage of the microsphere activity

{Tale 3).

At the same time that the aquaria were e~tied so that

the water could be analyzed, snails which hdd been added to

the aquaria to control algal growth were removed and analyzed

for plutonium (Table 4).

A second study was made using ticrospheres from Batch #1

(the batch used in soils for plant uptake studies) . AS before,

a single microsphere was placed in each aquarium which con-

tained about 26 litres of dechlorinated Los Alamos tap water.

After two days and ten days, one fish from each aquarium

was dissected and

After twenty days

died. These fish

organic co~ounds

the parts analyzed separately for plutonium.

of exposure all six fish in one aquarium

were killed by ingested toxic chlorinated

and not by the radioactivity in the aquaria.

The fecal matter from the six relatively large goldfish,

along with the fish food which had not been completely eaten

by the fish, began to deplete the o~gen in the water a~

noted by the behavior of the fish. TO alleviate this condi-

tion the fish were removed and the water waa treated

-8-

TABLE 3

Pu FOUND IN THE AQUARIA WATER AV OF 3 SAMPLES

%

MicrosphereActivity Found

in Water*

Total d/min AquariaCalculated

Contact Time

With 238Pu0~Av

E!Q&Q

2 656 3.8 x 10-2

1.7 x 10-2

9 days 69 056

17 days 1 172 20 472

6.9 X 10-3

3.1 x 10-3

49 days 484 12 585

72 days 218 5 668

5.2 X 10-3114 days 364 9 464

5.2 X 10-3

4.5 x 10-3

168 days 366 9 516

185 days** 314 8 164

*Assuming uniform distribution of plutoniumthroughout water

**Tetination

.

TABLE 4

PLUTONIUM FOUND IN SNAILS GROWN

AVG OF ALL SNAILS FOUND IN 3

.

Snail Flesh

. Snail Shell

IN 238PU02 SPZKED WATER

AQUARIA AFTER 185 DAYS

mh Dry

2,791 817

710 371

with sodium hypochlorite to oxidize the organic compounds

in the water. The water was then treated to remove residual

chlorine by the addition of sodium thiosulfate until the

water tested chlorine free, at which time the fish were re-

turned to Lhe aquazjum. This procedure had been used once

b&fore and proved to be successful. However, this time,

toxic uaqounds such as chlorarnir,esmay have formed and the

six fish died shotily after being returned to the aquarium.

The water in the effected aquarium was discarded and replaced

with fresh dechlorinated tap water.

The six fish which died were dissected and all like

P*8 were combined to form a single s~le such that the

#ix heads were analyzed as a single sample, six gut samples

combined and analyzed as a single sample, etc. At the same

time a fish from one of the other aquaria was sacrificed,

dissected and analyzed for plutonium. The remaining eleven

fish were distributed in t!~ethree aquaria so that two

aquaria had four fish each and one aquarium had three fi~h.

With only three or four fish in each aquarium the air bub-

blers were able to supply enough o~gen to the water to

sustain the goldfish.

Twenty-eight days later (forty-eight days after the

stu@ was ~nitiated) a fish from the two aquaria which had

four fish each was sa~srificed and analyzed for plutonium.

Three additional samplings (one fish from each aquarium)

made on the 72nd, l13th and 302nd day of the experiment

removed all the fish and

-9-

the experiment was terminated. The plutonium data gathered

from the analyses of fish parts are presented in Table 5 and

the data for water analyses presented in Table 6.

B. Discussion

From the data in Tables 2 and 5

each study the bulk of the plutonium

it is apparent that in

actitity incorporated

in the fish is located in the gills and gut. up to two

orders of magnitude more activity is found in the gut (with

contents) than is found in the fresh and bones.

The flesh from fish #21, Table 2, was found to contain

994 d/m/g of ash; this converts to about 17 d/m/g of wet

flesh since the flesh of these fi~h contains about 1.75Q

ash when dried at 105°C and ashed at 600°C; this plutonium

concentration is about 150% of the concentration guides (CG)

for plutonium in water for the 168 hour week given in AEC

Manual Appendix 0524, Annex A, November 1968.

It waF found that the fish along with snai1s and

algae apparently concentrate the plutonium present ia the

aquaria water. The gut of the fish (1.4% ash) contained

about 730 d/m/g of wet gut whereas the water (fish #21,

Table 2; water 185 day, Table 3) contained only 0.31 d/m/ml

which gives a concentration factor of a~>out2 300. The

flesh of fish #21 contained only 17 d/m\g of wet flesh which

represents a concentration factor (fish flesh to water) of

about 40. This indicates that almst all of the plutonium

taken into the gut is eliminated and does not find its way

-1o-

Exposure Tim

230 ‘nPU02 Watex

TABLE 5

PLUTONIUM IN BODY P= IN d/m/g OF ASH

2 days

10 days

20 days

48 days

72 days .

*113 days

302 days

Av of ntier of fish indicated

(Bat* #l,mkr0ephere9wed)

# ofFish Head Gill Flesh .Bones

3

3

7

2

3

3

3

0.46

0.47

0.22

0.93

0.61

0.65

0.41

GutGutOrgans

1.78

2.24

2.24

“2.02

2.50

2.40

9.0

0.36 0.72

0.28 0.14

0.35 0.75

0.65 0.36

0.65 0.43

0.42 0.25

0.57 0.44

3.6

60.8

27.2

24

35.8

35.1

24.3

0.95

0.75

1.60

4.6

4.9

4.4

12.5

*Highest % of microsphere activity found in fish was 4.2 x 10-6%.

.

.

.

TABLE 6

.

CONCENTRATION OF PU IN AQUARIA WATER

(Batch #l, microspheces used)

TirQeExposed

1

24

48

3

4

9

10

16

19

25

42

145

302

hr”

hrs

hrs

days

days

days

days

days

days

days

days

days

days

d/m/l of WaterW Of 3 Samples)

111*

88 -

45

53

24

68

49

45

29

72

3

- 1.4

.“

*Highest % of microsphere activity foundin water was 1.6 x 10-3%.

into the flesh or the edible portions of fish.

A single determination of plutonium in.an algal 0sample

in an earlier preliminary aquarium experimnt indicated a

concentration factor of about 2 000’. This was calculated

using tb plutonium concentrateion in algae expressed as

d/m/g of dry algae and the concentration of plutonium in

d/m/ml in the water sample after 24 hours (Table 5, i. e.

222 d/~q of dry alqae11

= 2 000.●

~t~econcentration factor would be an order of magnitude

less if the plutonium in the algae were expressed as d/m/g

of wet algae (assuming dry weight is 10% of the wet weight) .

When one compares the plutonium in snai:ls (Table 4)

expressed as d/m/g of dry flesh a concentration factor of

about 2 600 is obtained, i.e. d/m/q dry snail flesh/m/ml Pu in water ●

Alva.rez-Rzunis4 did not find a concentrating of plutonium in

snails.liting in soil contaminated with plutonium. However,

in that instance the plutonium concentration in the materiai

which passed through the digestive systems of the snai1.s

was not known and the plutonium mst certainIy was not

uniformly distributed in the soi but was present in the

soil as particulate plutonium oxide. These factors make it

impossible to detemnine a meaningful concentratmn factor

as was done in the aquaria experiments.

The fish used in a second comparable study (Batch *1

microsphere) showed little tendency to concentrate the

-11-

plutonium. For example, +-neten day fish sample (Table 5)

had only 60.8 d/m/g of ashed gut or 0.85 d/m/g of wet gut

- which wherecampared with water at 10 days (Table 6) would

give a concentration factor of only about 12, i.e ● ,

0 ● 85 d/m/g Of wet gut068 d of water at

=12. If one calculates● /m/ml days

the plutonium concentration for the 48 day fish sample (Table

5) on the basis of d/m/g of wet flesh using an ash content

of 1.75% and conpa.resthis value with the plutonium in

water at 42 days (Table 6), a concentration factor of about

0.15 is obtained, i.e. ~72.65 d/m/q of ash .x.0175 = 0.15 ●

9 /m/xnlin water at days

The reason for these smaller concentration factors

second study is not known at present but indicates#

ferences in batches of microsphere

If the assumption is made that

trate plutonium in a manner similar

referred to in

in the

the dif-

Part II.

commercial fish concen-

to that of goldfish

then commrci al fish could pose a slight radiological hazard

to man if the fish were in water containing238PU02 mic.ro-

spheres which were similar to Batch #2 microsphere canalak

the concentration used in these studies. At the plutonium

concentration levels used in the Batch #1 microsphere

studies the fish apparently

hazard when consumed by man

would pose no radiological

singe this batch of rnicrospheres

showed little tendency to become “appare..tlysolu.bilized”

in the tap water.

Pillai, et al.5 also found that marine organisms con-

centrate plutonium. They report plutonium concentration

-12-

factors for green algae of 1 570, zooplankton of 2 590 and

fish (Bonito) of 3 compared with plutonium found in sea

water. Wang, et al ● 6 found that Southern California

‘seWeeds n concentrate plutonium by factors of 260 to 3 500

tires greater than the concentration of plutonium in sea

water. 7Ward feun~ that lobster flesh from animals gran

in sea water contaixiing10-2 ~Ci/litre of 239Pu contained

three tixms the concentration of

water.

The plutonium concentration

at LASL are certainly within the

pl~tonium found in the sea

factors for

range found

algae found

~“ Wong for

“seaweeds.H The plutonium concentration factor for fish

flesh (Gatch #2 microsphere) was about fifteen ti=s

higher than that reported by Pillai for Bonito fisL, per-

haps reflecting differences in the species studies.

It is worthy of note that the microsphere probably

are not.all alike and may differ in their behavior in water.

For this reason it might be presumptuous to predict actual

contamination levels in water and associated animal life

on the basis of experimentation with a half dozen microsphere.

Note the vast differcnce in plutonium concentrations in

fish parts (Tables 2 and 5) and the difference in plutonium

concentrations in water when using different batches of micro-

sphere (Tables 3 and 6).

-13-

,,

c. 2%102 “ScJlubility” in Water

The variation in the plutonium analyses on aquaria

water (Table 3, Part 11A) prompted an experimental deter-

mination of t~Ae“solubility” of 238PU02 microsphere in tap

water in the absence of fish or algae. P.single microsphere

was placed in each of two beakers containing one litre of

Los Akmos Tap water. The water in each beaker was stirred

continuously with an electric stirring motor; ten ml sanples

of the water were removed At various time inte=vals and

analyzed for gross alpha activity. Evaporative losses were

co~ens ated for by the addition of distilled water, whereas

tap water was added in ~unts equal to that volume removed

for analysis. The gross alpha data are compiled in Table 7.

The rnicrosphereswhose dimeters were about 190 and

100 P were in contact with the water for 294 and 283 days

respectively.

the sam batch

in Part II A.

Both xnicrosphereswere obtained from Batch #2,

used in the first aquaria studies described

After the microsphere had been in the water

for the time indicated above, the water M as decmted ad

the microsphere recovered. The one litre samples of water

were analyzed for plutonium wing an micm e-~.changesepara-

tion procedure after conversion of the p~.utonium to the

PU(N03)6 = complex in 8 N HN03.

If all the plutonium found in the water at the comple-

tion of the experinnt is assumed to be “soluble,” then the

. -14-

#

.

TABLE“7

ALPHA ACTIVITY FOUND IN WATER CONTAINING

A BATCH #2 238Pu02

189 u DiamterMicrosphere

Cumulative Timei’kContact with Water

1 hr.

2 hrs

3 hrs

4 hrs

5 hrs

3 days

7 days

10 days

12 days

22 days

26 days

48 days

68 days

95 days

175 days

294 days

#

Gross a

~

280

11,000

440

“2bo

420

600

920

1+200

1,034

244,160

1,060

3,000

17,620

67,240

155,,060

173,480

MICROSPHERE

100 u DiameterMicrosphere

Cumulative Timein Contact with Water

1 hr

17 hrs

10 days

14 days

37 days

57 days

84 days “

164 days

283 days

Gross a

~

5,480

5,940

7,260

8,960

58,400

.12,394

15,720

28,720

54,140

238“volubility” of the PU02 can be determined and expressed

as a percentage of the original activity associated with -a

the microsphere. The original alpha activity of the micro-

sphere was.calculated by assuming a sphere and using the

approximate diameter of the microsphere (190 and 100 M,-“an

average density of 10.5 g/cc and the specific activity of

238PU9 The “volubility” data are presented in Table 8.#

Although the assumptions may not be exact, it is the rela-

tive “volubility” that is important.

In an earlier experimnt the 190 u microsphere used

in this study was placed in contact with tap water for 67

days. At the end of this time the microsphere was removed

from the water and the water was filtered through a 0.22 v

pore size millipore filter. The filter removed about 25%

of the alpha activity from the water. The apparent

‘Volubility” of 238PU02 calculated from the plutonium found

in the filtrate was 1.34 x 10-3% whereas the volubility

calculated from the alpha activity in the unfiltered water

-3was 1.8 x 10 8.

The millipore filter from the above filtration was

quartered and munted on NTA emulsion plates and the films

exposed from 4 1/2 to 103 hours. Using the method of

8Leary to calculate particle size from the number of alpha

tracks found on the developed film, particle sizes ranging

from 0.033 to 0.16 D diameter were calculated to be present

on the millipore filter; this indicates that at least part

-15-

.

TABIE 8-

23!Pu02 “MICR06PHERES IN TAP WATERVOLUBILITY OF -.

189 ~ Diamter =1OO ~ Di~ter -

294 Days Exposure . 283 Days Exposure

23~u FO~d 1.03 X 105 d/m/l238PU Found in Water = 2.88 x 105 d/@

8 Volubility-= O.0236% % Volubility = O.058%

Calc. Activity of

Microsphere =

.

.

238PU02 Calc. Activity of 238PU02

1.23 X 109 d/m Microsphere lkssumingloov

Dianeter = 1.82 X 108 d/m

W AIAM~ TAP

p~, 8.2

Conductivity , 116 @10/CIll

Phenol. alk, 0.0 mg/1

Total alk, 60 mg/1

Na+, 50 qll

Cl, 6.0 mgll

WATER

F- , 1.1 mg/1

Total hardness, 25 rng/1

Ca++, 9.0 mg/1

Mg++ , 0,5nlg/1

N03-N, 0.3 mg/1

Total Solids, 203 mg/1

.

of the pl’~tonium found in the water is particulate matter

and should not be considered as being in solution. The

particles found on the filter were smiler than the pore

size of the filter suggesting that these particles are

attached to larger nonradioactive particulate material.

D. Discussion of 238PU02 “Volubility” in Water.

Volubility in the classical sense implies the formation

of ions through the loss of electrons. AS related to

plutoriL:dand prabably sonm other elemnts, there is a

question as to whether the microcolloid or a group of atoms

spailed from macroparticles are ‘soluble.m As these-“solu-

tions” relate to filtration or transport in a DC field,

they appear to be true solutions, however, the fact that a

homogeneous solution is not formed is demonstrated by the

rango of activities determined for aliquots from the aanm

sample.

A correlative question to the lW uptake of plu20nium

by plants may be posed. Is the low uptake of plutonium

obsened in green plants a result of true solution in the

soil aqueous phase, and hence, is this more nearly a real

indication of the volubility of plutonium?

Results obtained from Nuclear Track Alpha (NTA) plates

lead one to suspect that what has been referred to as

“soluble” plutonium may in fact be particulate material

which would not be evidenced by classical chemistry but can

-16-

be demonstrated as present by radioautographic techniques.

The alpha activity, expressed as d/m/J. (Table 7)

which was calculated from the activity found in a ten

ml aliquot, sh~s considerable variation. These erratic

results could be caused by the breaking off of small parti-

238clea of PU02 which are not uniformly distributed in the

water.

9Lingren found that of the plutonium “in solution” fro-m

exposing 238PU02 microsphere to sea water, 22% migrated to

the anode, 23% to the cathode and 55% did not move in

electrochromatographic experiments. In a similar experiment

where plutanium was added as a solution to the sea water,

Lingren also found 30% of the plutonium migrated to the anode

whereas 70% did not move. Lingren suggests the formation

of a carbonate or hydroxide complex with a negative charge

resulting in movement tcward the anode. He also suggested

that the 55 or 70% of the plutonium which did not migrate

in the two experiments mentioned above might be a Pu (OH)~

neutral complex. Price10 mentions plutonium hydrolysis

products which are colloidal or exhibit colloidal behavior

and that these colloidal sized particles increase in size

with pH. Price also suggests that the form of plutonium

most likely to occur in natural waters or nuclear processing

waste streams is colloidal tetravalent plutonium as Pu(OH)~.

Unhydrolyzed plutonj,umexists in aqueous solutions of 0.1 M

hydrogen ion or greater. Precipitation of Pu(OH)~, the

-17-

end product of hydrolysis, begins at pH 2 or higher and

-3with Pu IV concentrations of 10 M.

Ockenden and Welchll state that during the intermediate

stages of hydrolysis there is polymerization of the hydro-

lyzed forms of Pu IV. This may occur through oxide or

hydroxide bridges with the formation of colloidal aggregates.

Lloyd and Haire12 in discussing the formationof plutonium

IV polymr stated that they do not

plutonium IV hydroxide species are

pitation of what was considered to

believe that monomeric

formed furing the preci-

be PU(OH)4. They do not

believe that monomeric Pu (OH) ~ is involved in the formation

of the “so called” plutonium IV polymer. They hi~ve pro-

posed that the initial precipitate consists of primary

patiicles which consist of or readily convert to very small

crystallite of hydrated PU02. These crystallites evidently

form clusters possibly accounting for the wide difference

in reported polymer aggregate size. Rhodes13 suggests the

existence of a polymr or radiocolloid with tracer concen-

trations of plutonium in solution at a pH greater than 2

but suggests that since the polymer is taken up rapidly by

the soil colloid it probably has a positive charge.

Kubose, et al.14 found in a static system for the

determination of 238PU02 solubi lity in sea water that essen-

tially all of the plutonium is sorbed on the material

settling to the bottom. Although the Los Alaxnos tap water

does not contain large amounts of dissolved salts (Table 8)

-18-

some material did form on the beaker during evaporation.

It is possible that some of the plutonium in the volubility

studies does sorb on that material.

The “volubility” (Table 8) expressed as a percentage

of the original activity of the 238PU02 microsphere is in

essential agree~nt with that found by Kubose, i.e. about

O.38% at 240 days exposure to sea water.

From a review of all data concerning “solubility”

of 238PU02 it appears possible that the plutonium in the

aquaria water and in the tap water is present as colloidal

Pu (OH)~ or hydrated PU02. H@ever, the plutonim could

also be present, at least partially, in very small fragments

of PU02 ● At the present time the chemistry of tracer con-

centrations of plutonium in waste water warrants further

study before one can be sure of the chemical or physical

state of the ~lutonium.

III. SUMMARY

Questions relative to the “volubility” of PU02 micro-

sphere have been posed. The use of plants as indicators

of true solubility of Pu02 microsphere has been su~gested.

Although several investigators have looked at the chemistry

of plutonium in solution it is apparent that further work

is required before one can draw conclusions concerning

“volubility” of refractory oxides of plutonium in water or

in soil.

-19-

9

References

1.

2.

3.

4.

s.

6.

7.

8.

9.

10.

R. C. Thompson,“SpaceNuclearSystemsStudies,“ Battelle Pacific

NorthwestLaboratory,BNWL-353Rev., 4-5 October1966..

AEC ManualAppendix0524AnnexA, November1968.

J. H. Harley,“WorldwidePlutoniumFalloutFrom WeaponsTests,”

Proc.EnvironmentalPlutoniumSymposium,Los Alams, New Mexico,

August 4-5, 1971, LA-4756,p. 78.

C. Alvarez-Ramis,A. Gregondesde 10S Santos,“Contaminationof

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Environment,“

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August 4-5,

E. E. Ward,

1971, LA-4756.

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by Radioautograph,” Anal.Chem. 23, 850, 1951.

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Dissolved Plutonium,” USNRDL-TRC-8S, September 1966.

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mcnt Practices, 1943-1971,BattelIe NorthwestLaboratoryReport

B3ML-B148(1971).

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14.

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D. W. Ockenden,G. A. Welch,“The Preparationand Propertiesof

Some PlutoniumCompounds- Part V, ColloidalQuadrivalentPluton-

ium,”J. Chem.Sot.,p. 3358 (1956).

M. H. Lloyd,R. G. Haire,“Studieson the Chemicaland Colloidal

Natureof Pu (IV)Polymer,”CONF-730927-2UNCLASDecember1973.

D. W. Rhodes,“Adsorptionof Plutoniumby Soil,“ Soil Sci. 84,

465 (1957).

D. A. Kubose,M. G. Lai,N. A. Goya,H. 1. Cordova,“Radioactivity

Releasefrom RadicluclidePower SourcesVIIa DissolutionStudies

of PlutoniumDioxidein the Ocean, 5 Mos. Exposure,”USNRDL-TR-

68-74 (1968).